Thermoplastic transparent resin composition and method of manufacturing same

ABSTRACT

Disclosed is a thermoplastic transparent resin composition and a method for manufacturing the same. The resin composition includes 3-15 parts by weight of small aperture polybutadiene rubber latex; 5-25 parts by weight of large aperture polybutadiene rubber latex; 40-70 parts by weight of a methacrylic acid alkylester compound or an acrylic acid alkylester compound; 15-30 parts by weight of an aromatic vinyl compound; and 1-20 parts by weight of a vinylcyan compound. The method includes the steps of a) producing a small aperture polybutadiene rubber latex having an average particle diameter of 600-1500 A, a gel content of 70-95%, and a swelling index of 12-30 by reacting butadiene at 55-70° C. using a polymerization initiator, b) producing a large aperture polybutadiene rubber latex having a particle diameter of 2600-5000 A, a gel content of 70-95%, and a swelling index of 12-30 by enlarging the small aperture polybutadiene rubber latex particles; c) performing graft copolymerization at 65-80° C. by continuously or separately adding 3-15 parts by weight of the small aperture polybutadiene rubber latex of step a), 5-25 parts by weight of the large aperture polybutadiene rubber latex of step b), 40-70 parts by weight of a methacrylic acid alkylester compound or an acrylic acid alkylester compound, 15-30 parts by weight of an aromatic vinyl compound, and 1-20 parts by weight of a vinylcyan compound.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national phase application of InternationalApplication No. PCT/KR99/00101, which was filed on Mar. 4, 1999 andwhich published in English on May 11, 2000, which in turn claimspriority from Korean Application No. 1998-45699, which was filed on Oct.29, 1998.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a thermoplastic transparent resincomposition, and more particularly, to a thermoplastic transparent resincomposition which is resistant to shocks, chemically resistant, easilyprocessed, and highly transparent. The present invention also relates toa method for manufacturing the thermoplastic transparent resincomposition in which, when performing graft copolymerization of amethacrylic acid or an acrylic alkylester compound, an aromatic vinylcompound, and a vinylcian compound in a mixture of a small aperturepolybutadiene rubber latex and a large aperture polybutadiene rubberlatex, both having a suitable gel content, a refraction coefficient ismaximized by controlling the mixture ratio of these monomers, therebyrealizing the advantages of the resin composition stated above.

(b) Description of the Related Art

Many various products today use transparent plastic parts for bothpractical reasons and to provide distinguishable characteristics to aproduct. Examples include the plastic screen cover on a cell phone, awashing machine cover that enables the user to view the contents beingwashed, portions of the housing of a PC monitor, pager housings, thehousings and covers of home appliances, etc. However, the typically usedABS (acrylonitrile-butadiene styrene) copolymer resin, althoughproviding good shock resistance, chemical resistance, processability,and surface gloss, has limited transparency.

The following are some of the methods for providing transparency inplastic materials:

1) A method using transparent polycarbonate resin.

2) A method of providing shock resistance to transparent PMMApolymethylmethacrylate) resin (U.S. Pat. No. 3,787,522, Japanese PatentNo. Sho 63-42940).

3) A method of providing transparency to HIPS (high impact polystyrene)resin (European Patent No. 0,703,252).

However, in the method of using polycarbonate resin, although thismaterial has good transparency and shock resistance at room temperature,it is not highly resistant to chemicals and does not display highresistance to shocks at low temperatures. This material also hasproblems related to processability, making it difficult to manufacturethis product to large sizes. With regard to PMMA resin, though providinggood transparency and processability, this material has an extremely lowlevel of resistance against shocks. Finally, regarding HIPS resin, thismaterial has a low level of resistance against chemicals and is easilyscratched.

U.S. Pat. No. 4,767,833, in an effort to solve the above problems,discloses a transparent resin in which monomers such asmethylmethacrylate, styrene and acrylonitrile are graft copolymerized inSBR (styrene-butadiene rubber) latex such that properties of shockresistance, chemical resistance, and processability are realized.However, this resin is limited in its resistance to shocks at lowtemperatures and displays a limited degree of transparency.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to solve the aboveproblems.

It is an object of the present invention to provide a thermoplastictransparent resin composition and a method of manufacturing the same inwhich the resin composition displays high resistance to shocks at bothroom temperature and low temperatures, high chemical resistance, goodprocessability, high surface gloss, and excellent transparency.

To achieve the above object the present invention provides athermoplastic transparent resin composition comprising 3-15 parts byweight of small aperture polybutadiene rubber latex, 5-25 parts byweight of large aperture polybutadiene rubber latex, 40-70 parts byweight of a methacrylic acid alkylester compound or an acrylic acidalkylester compound, 15-30 parts by weight of an aromatic vinylcompound, and 1-20 parts by weight of a vinylcian compound.

Further, the present invention provides a method of manufacturing athermoplastic transparent resin composition including the steps of a)producing a small aperture polybutadiene rubber latex having an averageparticle diameter of 600-1500 Å, a gel content of 70-95%, and a swellingindex of 12-30 by reacting butadiene at 55-70° C. using a polymerizationinitiator, b) producing a large aperture polybutadiene rubber latexhaving a particle diameter of 2600-5000 Å, a gel content of 70-95%, anda swelling index of 12-30 by enlarging the small aperture polybutadienerubber latex particles, and c) performing graft copolymerization at65-80° C. by continuously or separately adding 3-15 parts by weight ofthe small aperture polybutadiene rubber latex of step a), 5-25 parts byweight of the large aperture polybutadiene rubber latex of step b),40-70 parts by weight of a methacrylic acid alkylester compound or anacrylic acid alkylester compound, 15-30 parts by weight of an aromaticvinyl compound, and 1-20 parts by weight of a vinylcian compound.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

In the present invention, when producing an ABS resin comprised ofacrylonitrile having high chemical resistance, butadiene having goodresistance to shocks, and styrene providing good processability,methylmethacrylate is introduced, and by controlling a content andmixture ratio of each component, a refraction coefficient ofpolybutadiene rubber latex and a refraction coefficient of a mixture ofthe methymethacrylate, styrene, and acrylonitrile, grafted in the rubberlatex, are maximized. Accordingly, a thermoplastic transparent resin ismanufactured having high levels of shock resistance, chemicalresistance, and processability, in addition to excellent transparency.

The thermoplastic transparent resin composition of the present inventionis manufactured by graft copolymerizing, using an emulsionpolymerization method, a mixture of a small aperture polybutadienerubber having a particle diameter of 600-1500 Å, a gel content of70-95%, and a swelling index of 12-30 and a large aperture polybutadienerubber latex having a particle diameter of 2600-5000Å, a gel content of70-95%, and a swelling index of 12-30, and monomers grafted in themixture of a methacrylic acid or an acrylic acid alkylester compound, anaromatic vinyl compound, and a vinylcian compound.

The particle diameter and gel content of the polybutadiene rubber latexused in the present invention greatly influence properties of theinventive resin composition such as transparency and resistance toshocks. Therefore, particle diameter size and gel content must besuitably controlled to ensure that optimal levels of such properties arerealized. That is, in the case of the rubber latex particle size,although transparency is increased with decreases in particle size,shock resistance and fluidity are decreased, whereas the oppositeresults with increases in particle size. Further, if the gel content ofthe rubber latex is low, since the monomers undergo significant swellingin the rubber latex during graft reaction, an external particle diameterof the rubber latex is increased. This limits transparency but improvesresistance to shocks. Here also, the opposite effect results withincreases in the gel content.

Further, a refractive coefficient of the monomer mixture is directlyrelated to transparency of the inventive resin composition. Therefractive coefficient is controlled by a mixture ratio of the monomers.That is, since a refractive coefficient of polybutadiene isapproximately 1.518, the remaining grafted components must be similar tothis level to realize a high level transparency. Refractive coefficientsfor each component are 1.49 for the methylmethacrylate, 1.59 for thestyrene, and 1.518 for the acrylonitrile.

During the graft copolymerization reaction, each component can be addedall at once, or each separately (or partially for each component) in acontinuous manner. The present invention performs the adding ofcomponents using both these methods. This will be described in moredetail hereinafter.

A method of manufacturing the thermoplastic transparent resincomposition of the present invention will now be described.

1) Manufacture of Polybutadiene Rubber Latex

a) Manufacture of small aperture rubber latex

100 parts by weight of 1,3-butadiene, 1-4 parts, by weight of aemulsifying agent, 0.1-0.6 parts by weight of a polymerizationinitiator, 0.1-1.0 parts by weight of an electrolyte, 0.1-0.5 parts byweight of a molecular weight controlling agent, and 90-130 parts byweight of ion exchange water are added all at once, and reacted at50-65° C. for 7-12 hours. Next, 0.5-1.2 parts by weight of a molecularweight controlling agent is further added and reacted at 55-70° C. for5-15 hours, thereby producing small aperture polybutadiene rubber latexhaving an average particle diameter of 600-1500Å, a gel content of70-95%, and a swelling index of 12-30.

As the emulsifying agent, it is possible to use one or a mixture of twoor more of the following: alkyl aryl sulfonate, alkali methyl alkylsulfate, sulfonated alkylester, fatty acid soap, and rosin acid alkalisalt. As the polymerization initiator, it is possible to use a watersoluble persulfate or peroxy compound, or an oxidation-reductioncompound. The most suitable water soluble persulfates are sodium andpotassium. For a fat soluble polymerization initiator, it is possible touse cumene peroxide, diisopropyl benzene hydroperoxide,azobisisobutyronitrile, tertiary butyl hydroperoxide, paramethanehydroperoxide, and benzoyl peroxide. For the electrolyte, it is possibleuse one or a mixture of two or more of the following: KCl, NaCl, KHCO₃,NaHCO₃, K₂CO₃, Na₂CO₃, KHSO₃, NaHSO₃, K₄P₂O₇, K₃PO₄, Na₃PO₄, K₂HPO₄, andNa₂HPO₄.

An important factor in determining gel content and the swelling index ofthe rubber latex is polymerization temperature. The type of initiatorused also influences these two characteristics of the rubber latex.

b) Manufacture of large aperture rubber latex (small aperture rubberlatex adhesion process)

3.0-4.0 parts by weight of an acetic acid aqueous solution is slowlyadded over a period of one hour to 100 parts by weight of the smallaperture rubber latex having a particle diameter of 600-1500 Å, a gelcontent of 70-95%, and a swelling index of 12-30, thereby enlarging theparticle size. Stirring is then discontinued and a large aperture rubberlatex results, the large aperture rubber latex having a particlediameter of 2600-5000 Å, a gel content of 70-95%, and a swelling indexof 12-30.

To provide shock resistance to the rubber latex, although it is possibleto manufacture the large aperture rubber latex using a directpolymerization method (Japanese Laid-Open Patent No. 56136807), a longreaction time is required and the gel content level that can be obtainedis limited with this method. Accordingly, in order to produce a largeaperture rubber latex in a short amount of time while maintaining a highgel content, it is preferable, as described above, to first manufacturea small aperture rubber latex having a high gel content, then add anacidic material to the rubber latex to enlarge the particles, therebyproducing a large aperture rubber latex.

2) Manufacture of Graft Copolymerization Material

Graft copolymerized in a mixture of 3-15 parts by weight of the smallaperture polybutadiene rubber latex and 5-25 parts by weight of thelarge aperture polybutadiene rubber latex are 40-70 parts by weight of amethacrylic acid alkylester compound or an acrylic acid alkylestercompound, 15-30 parts by weight of an aromatic vinyl compound, 1-20parts by weight of a vinylcian compound, 0.2-0.6 parts by weight of anemulsifying agent, 0.2-0.6 parts by weight of a molecular weightcontrolling agent, and 0.05 to 0.3 parts by weight of a polymerizationinitiator.

In the above, a suitable polymerization temperature is 65-80° C., and asuitable polymerization time is 4-7 hours. In the polymerizationreaction, it is possible to use methymethacrylate for the methacrylicacid alkylester compound or acrylic acid alkylester compound; for thearomatic vinyl compound, it is possible to use styrene, α-methylstyrene,oethylstyrene, p-ethylstyrene, or vinyl toluene; and for the vinylciancompound, It is possible to use acrylonitrile, methacrylonitrile, orethacrylonitrile.

As the emulsifying agent used in the polymerization reaction, it ispossible to use one or a mixture of two or more of alkyl aryl sulfonate,alkali methyl alkyl sulfate, sulfonated alkylester, fatty acid soap, androsin acid alkali salt. For the molecular weight controlling agent,tertiary dodecyl mercaptan is, generally used. As the polymerizationinitiator, it is possible to use an oxidationreduction catalyst realizedthrough a mixture of (a) a peroxide such as cumene peroxide, diisopropylbenzene hydroperoxide, and persulfuric acid salt, and (b) a reducingagent such as sodium formaldehyde sulfoxylate, sodiumethylenediaminetetraacetic, primary iron sulfate, dextrose, pyrrolineacid sodium, and sulfurous sodium.

After polymerization is complete, a polymerization conversion rate ofthe obtained latex is over 98%. An oxidation preventing agent and astabilizer is then added to the latex, and at a temperature over 80° C.,the latex is coagulated using a calcium chloride aqueous solution, afterwhich the latex is desiccated and dried, thereby obtaining a powder.

Stability of the graft copolymerized latex manufactured in the above isdetermined by measuring a solidification rate (%) using Equation 1below.

[Equation 1 ]

Solidification (%)=produced solidification wt.(g) in reactor/weight ofall rubber and monomers X 100

A solidification rate of over 0.7% is indicative of an extremely lowlatex stability, and there will occur difficulty in realizing suitablegraft copolymerization as a result of the large presence of solidmaterial.

After adding the oxidation preventing agent and stabilizer, pellets aremanufactured from the powder using a biaxial extruding mixer at atemperature between 200 and 230° C. The pellets are again extracted tomeasure properties of the same.

Since the mixture of the monomers in the present invention changes therefraction coefficient in the resulting inventive resin, it is importantto obtain a suitable monomer mixture to realize good transparency. Thatis, since a refractive coefficient of polybutadiene is approximately1.518, an entire refractive coefficient of the grafted compound must be1.510-1.526, preferably between 1.513and 1.521. A refractive coefficientnot reaching 1.510 or exceeding 1.527 is not suitable in the presentinvention.

The present invention is further explained in more detail with referenceto the following examples. The invention can be utilized in various waysand is not intended to be confined to the examples.

EXAMPLE 1

I. Manufacture of polybutadiene rubber latex

A) Manufacture of small aperture rubber latex

Added all at once to a nitrogen substituted polymerization autoclavewere 110 parts by weight of ion exchange water; 100 parts by weight of1,3-butadiene as a monomer; 1.2 parts by weight of rosin acid potassiumsalt as a emulsifying agent; 1.5 parts by weight of oleic acid potassiumsalt; 0.1 parts by weight of sodium carbonate (Na₂CO₃) as electrolyte;0.5 parts by weight of potassium hydrogen carbonate (KHCO₃); and 0.3parts by weight of tertiary dodecyl mercaptan (TDDM) as a molecularweight controlling agent. Next, a reaction temperature was increased to55° C., and after adding 0.3 parts by weight of persulfuric acidpotassium as an initiator to begin the reaction, reaction was performedfor 10 hours. Following this step, 0.05 parts by weight of tertiarydodecyl mercaptan were again added to the mixture, after the same wasreacted for 8 hours at 65° C. A rubber latex obtained using this methodwas analyzed using a method described below.

(1) Gel content and swelling index

After solidifying the rubber latex using diluted acid or metal salt, therubber latex is washed then dried for 24 hours in a vacuum oven set at60° C. Subsequently, the obtained rubber lumps are cut in small(approximately 1g) pieces using scissors, and the pieces are put into100g of toluene then stored in a darkroom at room temperature for 48hours. After storage, the material is separated into sol and gel, and agel content and swelling index are measured using Equation 2 andEquation 3 below, respectively. [Equation 2]

Gel content (%) =weight of insoluble portion (gel)/weight of sample X100

[Equation 3]

Swelling index =weight of swelled gel/weight of gel

(2) Particle diameter

Particle diameter is measured by a dynamic laser light scattering methodusing a Nicomp 370 HPL.

Using the above methods, the gel content of the particle diameter was90%, the swelling index was 18, and the particle diameter was 1000 Å.

B) Manufacture of large aperture rubber latex (small aperture rubberlatex adhesion process)

Added to a reactor were 100 parts by weight of the small aperture rubberlatex manufactured above. Next, at a stirring speed of 10 rpm and atemperature of 30° C., 3.5 parts by weight of an acetic acid aqueoussolution were slowly added to the small aperture rubber latex over aperiod of one hour, after which stirring was discontinued and themixture was left to stand for 30 minutes, thereby completing themanufacture of the large aperture rubber latex. The large aperturerubber latex obtained through an adhesion method in this manner had aparticle diameter of 3000 Å, a gel content of 90%, and a swelling indexof 17.

II. Manufacture of graft copolymerization material

Added all at once at a temperature of 50° C. to a mixture of 8 parts byweight of the small aperture rubber latex and 10 parts by weight of thelarge aperture rubber latex were the components of Example 1 shown inTables 1 and 2, i.e. 90 parts by weight of ion exchange water, 0.2 partsby weight of an oleic acid sodium emulsifying agent, 11.98 parts byweight of methylmethacrylate, 4.52 parts by weight of styrene, 4 partsby weight of acrylonitrile, 0.2 parts by weight of tertiary dodecylmercaptan, 0.048 parts by weight of pyrophosphoric acid sodium, 0.012parts by weight of dextrose, 0.001 parts by weight of primary ironsulfate, and 0.04 parts by weight of cumene hydroperoxide. The mixturewas reacted while slowly increasing the temperature to 73° C. over aperiod of 2 hours.

Next, continuously added to the above mixture over a period of 4 hourswas an emulsifying agent mixture of 70 parts by weight of ion exchangewater, 0.4 parts by weight of an oleic acid sodium emulsifying agent,35.92 parts by. weight of methylmethacrylate, 13.58 parts by weight ofstyrene, 12 parts by weight of acrylonitrile, 0.25 parts by weight oftertiary dodecyl mercaptan, 0.048 parts by weight of pyrophosphoric acidsodium, 0.012 parts by weight of 5 dextrose, 0.001 parts by weight ofprimary iron sulfate, and 0.10 parts by weight of cumene hydroperoxide.The temperature was again increased to 76° C. over a period of one hourto mature the mixture, thereby completing the reaction.

A polymerization conversion rate of the obtained latex was 99.8% and asolidification rate of the same was 0.12%. A powder was obtained bysolidifying lo the latex using a calcium chloride aqueous solution thenwashing the same.

EXAMPLE 2

The same method as in Example 1 was used to manufacture small and largeaperture rubber latex, and graft copolymerization material, but acomposition ratio for Example 2 shown in Tables 1 and 2 was used insteadof that for Example 1.

COMPARATIVE EXAMPLES 1-5

The same method as in Example 1 was used to manufacture small and largeaperture rubber latex, and graft copolymerization material, bud acomposition ratio for Comparative Examples 1-5 shown in Tables 1 and 2was used instead of that for Example 1.

COMPARATIVE EXAMPLE 6

The same method as in Example 1 was used to manufacture small aperturerubber latex and graft copolymerization material, but a compositionratio for Comparative Example 6 shown in Tables 1 and 2 was used insteadof that for Example 1. Large aperture rubber latex in ComparativeExample 6 was manufactured as described below.

Manufacture of large aperture rubber latex (direct polymerization 5method)

Added all at once to a nitrogen substituted polymerization autoclavewere 83 parts by weight of ion exchange water; 100 parts by weight of1,3-butadiene; 1.2 parts by weight of rosin acid potassium salt as anemulsifying agent; 1.5 parts by weight of oleic acid potassium salt; 0.7parts by weight of sodium carbonate (Na₂CO₃) as electrolyte; 0.8 partsby weight of potassium hydrogen carbonate (KHCO₃); and 0.3 parts byweight of tertiary dodecyl mercaptan (TDDM) as a molecular weightcontrolling agent. Next, a reaction temperature was increased to 65° C.,and after adding 0.3 parts by weight of persulfuric acid potassium as aninitiator to initiate the reaction, reaction was performed for 45 hourswhile the temperature was raised to 85° C. A rubber latex obtained usingthis method was then analyzed, the results of which were a rubber latexhaving a particle diameter of 3000 A, a gel content of 65%, and aswelling index of 31.

APPLIED EXAMPLE 1

Added to 100 parts by weight of the graft copolymerization material ofExample 1 were 0.1 parts by weight of an activator and 0.2 parts byweight of an oxidation preventing material. Next; using a biaxialextruding mixer, pellets were made from the graft copolyrnerizationmaterial and added components in a cylinder oven set at 210° C. Thepellets were extracted to make samples, and. properties of the sampleswere measured, results of which are shown in Table 3.

APPLIED EXAMPLES 2-8

The same method as that used in Applied Example 1 was used, but insteadof adding the materials to the graft copolymerization material ofExample 1, the powder manufactured according to Example 2 andComparative Examples 1-6 was used for Applied Examples 2-8,respectively. Results of analysis are shown in Table 3.

TABLE 1 Comp. Comp. Comp. Comp. Comp. Comp. 1^(st) Example ExampleExample Example Example Example Example Example Reaction 1 2 1 2 3 4 5 6Ion Exch. 90 100 99 91 96 92 90 95 Water Small Apert. 8 3 1 4 6 14 — 4Rubber Latex Large Apert. 10 9 9 8 10 — 14 10 Rubber Latex (directmethod) Oleic Acid 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 SodiumMethylmethacrylate 11.98 — — 15.8 — — 14.38 19.2 Styrene 4.52 — — 3.7 —— 5.63 7.47 Acrylonitrile 4 — — 2.5 — — 2.5 2 Tertiary 0.2 — — 0.2 — —0.2 0.2 dodecyl mercaptan Pyrophosphoric 0.048 0.048 0.048 0.048 0.0480.048 0.048 0.048 acid sodium Dextrose 0.012 0.012 0.012 0.012 0.0120.012 0.012 0.012 Primary 0.001 0.001 0.001 0.001 0.001 0.001 0.0010.001 iron sulfate Cumene 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04hydroperoxide Add. batch batch batch batch batch batch batch batchMethod Reaction 2 hours — — 2 hours — — 2 hours 2 hours Time

TABLE 2 Comp. Comp. Comp. Comp. Comp. Comp. 2^(nd) Example ExampleExample Example Example Example Example Example Reaction 1 2 1 2 3 4 5 6Ion Exch. 70 60 61 69 64 65 70 65 Water Oleic Acid 0.6 0.4 0.35 0.42 0.50.5 0.4 0.5 Sodium Methylmethacrylate 35.92 62.13 64.8 47.4 49.68 57.643.12 38.4 Styrene 13.58 22.87 25.2 11.1 26.32 22.4 16.88 14.93Acrylonitrile 12 3 — 7.5 8 6 7.5 4 Tertiary 0.25 0.25 0.25 0.25 0.250.25 0.25 0.25 dodecyl mercaptan Pyrophosphoric 0.048 0.048 0.048 0.0480.048 0.048 0.048 0.048 acid sodium Dextrose 0.012 0.012 0.012 0.0120.012 0.012 0.012 0.012 Primary 0.001 0.001 0.001 0.001 0.001 0.0010.001 0.001 iron sulfate Cumene 0.1 0.11 0.1 0.1 0.1 0.1 0.1 0.1hydroperoxide Add. Method Continuous continuous continuous continuouscontinuous continuous continuous continuous Reaction Time 4 hours 6hours 6 hours 4 hours 6 hours 6 hours 4 hours 4 hours Polymer. 99.8 99.099.7 99.7 99.5 99.5 99.3 99.8 Conv. Rate (%) Solidification (%) 0.120.10 0.10 0.10 0.15 0.10 0.10 0.10

TABLE 3 Applied Applied Applied Applied Applied Applied Applied AppliedEx. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Graft Example ExampleComp. Comp. Comp. Comp. Comp. Comp. copolymerization 1 2 Example ExampleExample Example Example Example material 1 2 3 4 5 6 Notch Isod 16 11 710 14 3 13 13 Shock Strength ASTM D-256 Fluidity Index 14 22 25 22 16 1618 19 ASTM D-1238 Haze value 3.5 3 3.9 20 24 2.4 8.8 11.2 ASTM D-1003Chemical Resist. Extremely High Low High High High High High (ethanolsolution) High (after 14-day storage)

Although preferred examples of the present invention have been describedin detail hereinabove, it should be clearly understood that manyvariations and/or modifications of the basic inventive concepts hereintaught which may appear to those skilled in the present art will stillfall within the spirit and scope of the present invention, as defined inthe appended claims.

1. A thermoplastic transparent resin composition comprising: 3-15 partsby weight of small aperture polybutadiene rubber latex; 5-25 parts byweight of large aperture polybutadiene rubber latex; 40-70 parts byweight of a methacrylic acid alkylester compound or an acrylic acidalkylester compound; 15-30 parts by weight of an aromatic vinylcompound; and 1-20 parts by weight of a vinylcian compound, wherein thesmall aperture polybutadiene rubber latex has a particle diameter of600-1500 Å, a gel content of 70-95%, and a swelling index of 12-30, andthe large aperture polybutadiene rubber latex has a particle diameter of2600-5000 Å, a gel content of greater than 80 and not exceeding 95%, anda swelling index of 12-30, wherein the large aperture polybutadienerubber latex with a gel content of greater than 80 and not exceeding 95%is produced by adhering small aperture polybutadiene rubber latexparticles with a gel content of 70-95%, wherein a total refractioncoefficient of the composition, excluding the polybutadiene rubberlatex, is between 1.510 and 1.526.
 2. The resin composition of claim 1wherein the composition further comprises 0.2-0.6 parts by weight of anemulsifying agent, 0.2-0.6 parts by weight of a molecular weightcontrolling agent, and 0.05-0.3 parts by weight of a polymerizationstarter.
 3. The resin composition of claim 1 wherein the methacrylicacid alkylester compound and the acrylic acid alkylester compound aremethylmethacrylate.
 4. The resin composition of claim 1 wherein thearomatic vinyl compound is selected from the group consisting ofstyrene, α-methylstyrene, o-ethylstyrene, p-ethylstyrene, and vinyltoluene.
 5. The resin composition of claim 1 wherein the vinylciancompound is selected from the group consisting of acrylonitrile,methacrylonitrile, and ethacrylonitrile.
 6. A method of manufacturing athermoplastic transparent resin composition comprising the steps of: (a)producing a small aperture polybutadiene rubber latex having an averageparticle diameter of 600-1500 Å, a gel content of 70-95%, and a swellingindex of 12-30 by reacting butadiene at 55-70° C. using a polymerizationinitiator; (b) producing a large aperture polybutadiene rubber latexhaving a particle diameter of 2600-5000 Å, a gel content of greater than80 and not exceeding 95%, and a swelling index of 12-30 by adhering thesmall aperture polybutadiene rubber latex particles; and (c) performinggraft copolymerization at 65-80° C. by continuously or separately adding3-15 parts by weight of the small aperture polybutadiene rubber latex ofstep (a), 5-25 parts by weight of the large aperture polybutadienerubber latex of step (b), 40-70 parts by weight of a methacrylic acidalkylester compound or an acrylic acid alkylester compound, 15-30 partsby weight of an aromatic vinyl compound, and 1-20 parts by weight of avinylcian compound, wherein a total refraction coefficient of thecomposition, excluding the polybutadiene rubber latex, is between 1.510and 1.526.
 7. The method of claim 6 wherein the methacrylic acidalkylester compound and the acrylic acid alkylester compound aremethylmethacrylate.
 8. The method of claim 6 wherein the aromatic vinylcompound is selected from the group consisting of styrene,α-methylstyrene, o-ethylstyrene, p-ethylstyrene, and vinyl toluene. 9.The method of claim 6 wherein the vinylcian compound is selected fromthe group consisting of acrylonitrile, methacrylonitrile, andethacrylonitrile.